T-4 Free Energy

Question 1

Define Gibb’s Free Energy

Answer 1

Amount of work a spontaneous process can do on its surroundings or the amount of work the surrounds must do to drive a nonspontaneous process

Question 2

How is free energy related to enthalpy and entropy (equation)?

Answer 2

delta G = delta H - T•delta S

Question 3

How is delta Gº related to delta G (equation)?

Answer 3

delta G = delta Gº + RT ln(Q)

Question 4

How is delta Gº related to K (equation)?

Answer 4

delta Gº = -RT ln(K)

Question 5

What is the sign of delta G when a process is spontaneous?

Answer 5

negative

Question 6

At what temperature is a process spontaneous when…

delta H is positive

delta S is positive

Answer 6

At high temperatures -T delta S is larger than delta H

(T= delta H / delta S)

Question 7

At what temperature is a process spontaneous when…

delta H is positive

delta S is negative

Answer 7

never spontaneous

Question 8

At what temperature is a process spontaneous when…

delta H is negative

delta S is negative

Answer 8

Low temperature so that - delta H is greater than + (- of -) T delta S

(T= delta H / delta S is negative)

Question 9

At what temperature is a process spontaneous when…

delta H is negative

delta S is positive

Answer 9

At all temperatures

Question 10

What is the value for delta G when a system is at equilibrium?

Answer 10

delta G = 0

Question 11

Is the following system shifting to the right, shifting to the left, or at equilibrium?

delta G is negative

Answer 11

Shift right

Question 12

Is the following system shifting to the right, shifting to the left, or at equilibrium?

delta G is zero

Answer 12

at equilibrium

Question 13

Is the following system shifting to the right, shifting to the left, or at equilibrium?

delta G is positive

Answer 13

shifting to the left

Question 14

What is happening to the value of delta G as a reaction shifts to the left

Answer 14

The positive delta G is getting smaller as it heads towards delta G = 0

Question 15

What is happening to the value of delta G as a reaction shifts to the right?

Answer 15

The magnitide of the negative delta G is getting smaller as it heads towards delta G = 0

Question 16

What can you tell me about the value of K for a reaction with a negative delta Gº?

Answer 16

K > 1

delta Gº = -RT ln(K)

Question 17

What can you tell me about the value of K for a reaction with a positive delta Gº?

Answer 17

K < 1

delta Gº = -RT ln(K)

Question 18

What can you tell me about the value of K for a reaction with a delta Gº = 0?

Answer 18

K = 1

delta Gº = -RT ln(K)

Question 19

Delta G for a process at low temperatures is negative. No product is observed to be forming. Commnet on the thermodynamic and kinetic favorability of the reaction.

Answer 19

The reaction is thermodynamically favorable (delta G is negative). Since is does not appear to proceed then it must by kinetically unfavorable (it is very slow).